Prior systems for exhausting food fumes and smoke from commercial cooking apparatus, such as ovens and food fryers, required the exhaust to be vented out of the building since it was not formerly possible to clean and deodorize grease-laden air sufficiently for recirculation into the room. Exhausting grease-laden fumes from a high-rise building is often difficult and costly. Known venting systems which discharge cooking fumes to the outside atmosphere may provide adequate air quality within the building, but air pollution outside the building from the cooking fumes may be malodorous to people passing in the street.
Stamps, U.S. Pat. No. 4,489,647, describes a ventless exhaust system only for use with an enclosed, small-scale, unpressurized, food frying and dispensing apparatus for cooking individual portions of food for which a short cooking cycle is sufficient and only a small quantity of grease-laden exhaust air is produced.
The patent to Glover, U.S. Pat. No. 3,747,301, describes a smoke eliminator for use above burners or grills, but does not address the problem of cleaning exhaust from large scale ovens or fryers sufficiently for recirculation. Gaylord, U.S. Pat. No. 3,785,124, includes a grease extractor hood section and a deodorizing section in order to purify air being vented to the outside atmosphere. King, U.S. Pat. No. 3,907,525, describes a similar system for cleaning air before exhausting it to the atmosphere. The patent to Ebert, U.S. Pat. No. 3,744,217, describes a high-voltage ozone-free electrostatic air filter suitable for use over a kitchen oven.
Other patents, such as those to Kuechler, U.S. Pat. Nos. 3,952,640 and 4,085,736 and 4,250,870, describe a vortex system for exhausting air.